Optimization of offset frequency in the SORC pulse sequence using feedback.

The low signal-to-noise ratio (SNR) of nuclear quadrupolar resonance measurements has motivated research on signal enhancement methods, including multipulse sequences that facilitate signal averaging, the development of interlaced pulse sequences, and super-Q coils. More recently, it has been shown that feedback can be used to automatically optimize pulse sequence parameters, maximizing the SNR. This paper extends this work by using feedback to optimize the offset frequency in the strong off-resonant comb pulse sequence. Analysis and results are presented for a sample of sodium nitrite at both liquid nitrogen and room temperatures.